IRR 可以點用人手計?

IRR 一般都是用 EXCEL 或 PROGRAMABLE CALCULATOR 來計算, 很難用"人手" 來計算. 下面的資料 節錄自維京百科:
Given a collection of pairs (time, cash flow) involved in a project, the internal rate of return follows from the net present value as a function of the rate of return. A rate of return for which this function is zero is an internal rate of return.Given the (period, cash flow) pairs (n, Cn) where n is a positive integer, the total number of periods N, and the net present value NPV, the internal rate of return is given by r in:
圖片參考：http://upload.wikimedia.org/math/d/f/0/df0b3423bc7412d11b3871c2333fff89.png
Note that the period is usually given in years, but the calculation may be made simpler if r is calculated using the period in which the majority of the problem is defined (e.g., using months if most of the cash flows occur at monthly intervals) and converted to a yearly period thereafter.Note that any fixed time can be used in place of the present (e.g., the end of one interval of an annuity); the value obtained is zero if and only if the NPV is zero.In the case that the cash flows are random variables, such as in the case of a life annuity, the expected values are put into the above formula.Often, the value of r cannot be found analytically . In this case, numerical methods or graphical methods must be used.ExampleIf an investment may be given by the sequence of cash flowsYear (n) Cash Flow (Cn)0−400011200214103187541050
then the IRR r is given by
圖片參考：http://upload.wikimedia.org/math/3/3/5/335358cd1e702118753812cbd52beb9f.png
.In this case, the answer is 14.3%.
希望幫到你.

我補充：
你知道下面的算式後，亦只能大約 試放一個假設的 r 值進去，例如10%，然後計算一下，發現計出來的npv，比真的NPV大，這樣你就試把 r 值 調高。例如15% ，這次npv比NPV 少了；你就再試把 r 值 調低....反覆計算，便會逼近真的 IRR。


圖片參考：http://upload.wikimedia.org/math/3/3/5/335358cd1e702118753812cbd52beb9f.png





ExampleIf an investment may be given by the sequence of cash flowsYear (n) Cash Flow (Cn)0−400011200214103187541050
then the IRR r is given by
圖片參考：http://upload.wikimedia.org/math/3/3/5/335358cd1e702118753812cbd52beb9f.png
.In this case, the answer is 14.3%.

2010-11-20 02:48:31 補充：
人手計 IRR，就是這樣 笨實的！